Field of the Invention
This invention relates to systems and methods for monitoring and controlling HVAC systems, and more particularly to a system which continuously monitors the HVAC system and determines if maintenance is required.
Description of Related Art
It is important to maintain heating, ventilating, and air conditioning (HVAC) systems in good working order to maintain optimum energy efficiency. Clogged filters reduce the ability of the HVAC system to circulate air, reducing effectiveness and requiring more energy. As it is generally difficult to determine the condition of a filter, most filter replacements are performed on a time basis, or a total-operating-hours basis. This can lead to a loss of efficiency if the filter becomes clogged unusually quickly (for example, due to heavy pollution in the area), or a wasted filter replacement if the filter has not yet become significantly clogged.
The prior art teaches filter sensor systems that can determine and report when a filter becomes clogged by monitoring changes in current and voltage. Keown, U.S. Pat. No. 6,842,117, teaches a filter condition sensing circuit is disclosed including current and voltage sensors and a computer processor. The current and voltage sensors produce signals indicating magnitudes of electrical current and voltage, respectively, provided to an electric motor used to move a fluid (a gas or liquid) through a filter element. During a first time period, the computer processor uses the signals to determine an acceptable range of electrical power required by the motor. During a second time period, the computer processor uses the signals to determine a magnitude of electrical power required by the motor. When the magnitude of electrical power is within the acceptable range of electrical power, the computer processor generates a signal indicating a normal condition of the filter element.
While this reference teaches monitoring the system, it is not able to take any action itself in the event of the filter becoming clogged, it can only report that the filter requires replacement.
In addition to monitoring the condition of the filter associated with the HVAC system, it is also important to monitor the status of the system itself, to detect mechanical problems that can lead to inefficient operation and also to failure of the system.
Other prior art systems measure other parameters of the HVAC system to determine the operational efficiency of the system, and to report potential mechanical problems, based upon measured differences in temperature. For example, Hoog et al., U.S. Pat. No. 6,385,510, teaches an HVAC monitoring computer that monitors the condition and efficiency of the HVAC system based upon measured differences in temperature (input vs, output), and notifies a central computer when the condition or efficiency falls below a certain industry standard.
While this prior art system teaches the monitoring of the HVAC system, it does not enable active control over the system. The present invention teaches a system that enables monitoring of the HVAC system similar to the prior art device, but also enables active control over the system using existing network architecture, as described in the following summary.